Spatial sound field reproduction techniques utilize a multiplicity of loudspeakers to create a virtual auditory scene over a large listening area. Several sound field reproduction techniques, for example, wave field synthesis (WFS) or Ambisonics, make use of a loudspeaker array equipped with a plurality of loudspeakers to provide a highly detailed spatial reproduction of an acoustic scene. In particular, wave field synthesis is used to achieve a highly detailed spatial reproduction of an acoustic scene to overcome limitations by using an array of, for example, several tens to hundreds of loudspeakers.
Spatial sound field reproduction techniques overcome some of the limitations of stereophonic reproduction techniques. However, technical constraints prohibit the employment of a high number of loudspeakers for sound reproduction. WFS and Ambisonics are two similar types of sound field reproduction. Though they are based on different representations of the sound field (the Kirchhoff-Helmholtz integral for WFS and the spherical harmonic expansion for Ambisonics), their aim is congruent and their properties are alike. Analysis of the existing artifacts of both principles for a circular setup of a loudspeaker array came to the conclusion that Higher-Order Ambisonics (HOA), or more exactly near-field-corrected HOA, and WFS meet similar limitations. Both WFS and HOA and their unavoidable imperfections cause some differences in terms of the process and quality of the perception. In HOA, with a decreasing order of the reproduction, the impaired reconstruction of the sound field will probably result in a blur of the localization focus and a certain reduction in the size of the listening area.
For audio reproduction techniques such as WFS or Ambisonics, the loudspeaker signals are typically determined according to an underlying theory, so that the superposition of sound fields emitted by the loudspeakers at their known positions describes a certain desired sound field. Typically, the loudspeaker signals are determined assuming free-field conditions. Therefore, the listening room should not exhibit significant wall reflections, because the reflected portions of the reflected wave field would distort the reproduced wave field. In many scenarios such as the interior of a car, the necessary acoustic treatment to achieve such room properties may be too expensive or impractical.